diff --git a/mozilla/layout/html/table/src/nsTableCellFrame.cpp b/mozilla/layout/html/table/src/nsTableCellFrame.cpp
index 3e6a773072e..548245b17ef 100644
--- a/mozilla/layout/html/table/src/nsTableCellFrame.cpp
+++ b/mozilla/layout/html/table/src/nsTableCellFrame.cpp
@@ -68,12 +68,6 @@ NS_METHOD nsTableCellFrame::Paint(nsIPresContext& aPresContext,
     nsCSSRendering::PaintBackground(aPresContext, aRenderingContext, this,
                                     aDirtyRect, rect, *myColor, 0, 0);
     
-    //XXX: this could be calculated once and remembered
-    // get border padding values
-    //XXX: also check style for rule on rendering empty cells
-    /*
-
-    */
     // empty cells do not render their border
     PRBool renderBorder = PR_TRUE;
     if (PR_TRUE==GetContentEmpty())
@@ -729,45 +723,6 @@ nscoord nsTableCellFrame::GetBorderWidth(nsIFrame* aFrame, PRUint8 aEdge) const
 }
 
 
-/**
-  * Given a style context and an edge, find the padding
-  *
-  **/
-nscoord nsTableCellFrame::GetPadding(nsIFrame* aFrame, PRUint8 aEdge) const
-{
-  nscoord result = 0;
-
-  if (aFrame)
-  {
-    const nsStyleSpacing* spacing;
-    aFrame->GetStyleData(eStyleStruct_Spacing, (const nsStyleStruct*&)spacing);
-    nsMargin  padding;
-    spacing->CalcPaddingFor(aFrame, padding);
-    switch (aEdge)
-    {
-      case NS_SIDE_TOP:
-        result = padding.top;
-      break;
-
-      case NS_SIDE_RIGHT:
-        result = padding.right;
-      break;
-
-      case NS_SIDE_BOTTOM:
-        result = padding.bottom;
-      break;
-
-      case NS_SIDE_LEFT:
-        result = padding.left;
-      break;
-
-    }
-  }
-  return result;
-}
-
-
-
 /**
   * Given an Edge, find the opposing edge (top<-->bottom, left<-->right)
   *
@@ -876,6 +831,7 @@ void nsTableCellFrame::RecalcLayoutData(nsTableFrame* aTableFrame,
   mCalculated = NS_OK;
 }
 
+
 /* ----- debugging methods ----- */
 NS_METHOD nsTableCellFrame::List(FILE* out, PRInt32 aIndent, nsIListFilter *aFilter) const
 {
diff --git a/mozilla/layout/html/table/src/nsTableCellFrame.h b/mozilla/layout/html/table/src/nsTableCellFrame.h
index 6bd3e74f288..dce0738f811 100644
--- a/mozilla/layout/html/table/src/nsTableCellFrame.h
+++ b/mozilla/layout/html/table/src/nsTableCellFrame.h
@@ -137,8 +137,6 @@ private:
 
   nscoord GetBorderWidth(nsIFrame* aFrame, PRUint8 aEdge) const;
 
-  nscoord GetPadding(nsIFrame* aFrame, PRUint8 aEdge) const;
-
   PRUint8 GetOpposingEdge(PRUint8 aEdge);
 
   void CalculateBorders(nsTableFrame* aTableFrame,
diff --git a/mozilla/layout/html/table/src/nsTableFrame.cpp b/mozilla/layout/html/table/src/nsTableFrame.cpp
index fbc069f03d4..51338353afd 100644
--- a/mozilla/layout/html/table/src/nsTableFrame.cpp
+++ b/mozilla/layout/html/table/src/nsTableFrame.cpp
@@ -1178,7 +1178,9 @@ void nsTableFrame::AppendLayoutData(nsVoidArray* aList, nsTableCellFrame* aTable
   }
 }
 
-void nsTableFrame::RecalcLayoutData()
+/* compute all the collapsed borders between aStartRowIndex and aEndRowIndex, inclusive */
+void nsTableFrame::ComputeCollapsingBorders(PRInt32 aStartRowIndex,
+                                            PRInt32 aEndRowIndex)
 {
   nsCellMap *cellMap = GetCellMap();
   if (nsnull==cellMap)
@@ -1186,6 +1188,77 @@ void nsTableFrame::RecalcLayoutData()
 
   PRInt32 colCount = cellMap->GetColCount();
   PRInt32 rowCount = cellMap->GetRowCount();
+  if (aStartRowIndex>=rowCount)
+  {
+    NS_ASSERTION(PR_FALSE, "aStartRowIndex>=rowCount in ComputeCollapsingBorders");
+    return; // we don't have the requested row yet
+  }
+
+  // For every row between aStartRowIndex and aEndRowIndex (or the end of the table),
+  // walk across every edge and compute the border at that edge.
+  // Distribute half the computed border to the appropriate adjacent objects
+  // (always a cell frame or the table frame.)  In the case of odd width, 
+  // the object on the right/bottom gets the extra portion
+  PRInt32 rowIndex = aStartRowIndex;
+  for ( ; rowIndex<rowCount && rowIndex <=aEndRowIndex; rowIndex++)
+  {
+    PRInt32 colIndex=0;
+    for ( ; colIndex<colCount; colIndex++)
+    {
+      /*
+      
+      // compute vertical edges
+      if (0==colIndex)
+      { // table is left neighbor
+        ComputeLeftBorderForEdgeAt(rowIndex, colIndex);
+      }
+      ComputeRightBorderForEdgeAt(rowIndex, colIndex);
+
+      // compute horizontal edges
+      if (0==rowIndex)
+      {
+        ComputeTopBorderForEdgeAt(rowIndex, colIndex);
+      }
+      ComputeBottomBorderForEdgeAt(rowIndex, colIndex);
+
+
+      if ((colCount-1)==colIndex)
+      { // table is right neighbor
+      }
+      else
+      { // interior cell
+      }
+
+      if ((rowCount-1)==rowIndex)
+      {
+      }
+      else
+      {
+      }
+
+      */
+
+    }
+  }
+}
+
+void nsTableFrame::RecalcLayoutData()
+{
+  nsCellMap *cellMap = GetCellMap();
+  if (nsnull==cellMap)
+    return; // no info yet, so nothing useful to do
+  PRInt32 colCount = cellMap->GetColCount();
+  PRInt32 rowCount = cellMap->GetRowCount();
+  
+  // compute all the collapsing border values for the entire table
+  // XXX: it would be nice to make this incremental!
+  const nsStyleTable *tableStyle=nsnull;
+  GetStyleData(eStyleStruct_Table, (const nsStyleStruct *&)tableStyle);
+  if (NS_STYLE_BORDER_COLLAPSE==tableStyle->mBorderCollapse)
+    ComputeCollapsingBorders(0, rowCount-1);
+
+  //XXX need to determine how much of what follows is really necessary
+  //    it does collapsing margins between table elements
   PRInt32 row = 0;
   PRInt32 col = 0;
 
@@ -3591,17 +3664,6 @@ void nsTableFrame::MapBorderMarginPadding(nsIPresContext& aPresContext)
 }
 
 
-
-
-// Subclass hook for style post processing
-NS_METHOD nsTableFrame::DidSetStyleContext(nsIPresContext& aPresContext)
-{
-#ifdef NOISY_STYLE
-  printf("nsTableFrame::DidSetStyleContext \n");
-#endif
-  return NS_OK;
-}
-
 NS_METHOD nsTableFrame::GetCellMarginData(nsTableCellFrame* aKidFrame, nsMargin& aMargin)
 {
   nsresult result = NS_ERROR_NOT_INITIALIZED;
diff --git a/mozilla/layout/html/table/src/nsTableFrame.h b/mozilla/layout/html/table/src/nsTableFrame.h
index 9c6b10ef4ef..32fbc182b63 100644
--- a/mozilla/layout/html/table/src/nsTableFrame.h
+++ b/mozilla/layout/html/table/src/nsTableFrame.h
@@ -207,6 +207,10 @@ public:
           
   /** Calculate Layout Information */
   void    AppendLayoutData(nsVoidArray* aList, nsTableCellFrame* aTableCell);
+
+  /* compute all the collapsed borders between aStartRowIndex and aEndRowIndex, inclusive */
+  void    ComputeCollapsingBorders(PRInt32 aStartRowIndex, PRInt32 aEndRowIndex);
+
   void    RecalcLayoutData();
 
   // Get cell margin information
@@ -473,8 +477,6 @@ public:
   virtual void InvalidateColumnWidths();
 
 protected:
-  /** do post processing to setting up style information for the frame */
-  NS_IMETHOD DidSetStyleContext(nsIPresContext& aPresContext);
 
   /** Support methods for DidSetStyleContext */
   void      MapBorderMarginPadding(nsIPresContext& aPresContext);
diff --git a/mozilla/layout/tables/nsTableCellFrame.cpp b/mozilla/layout/tables/nsTableCellFrame.cpp
index 3e6a773072e..548245b17ef 100644
--- a/mozilla/layout/tables/nsTableCellFrame.cpp
+++ b/mozilla/layout/tables/nsTableCellFrame.cpp
@@ -68,12 +68,6 @@ NS_METHOD nsTableCellFrame::Paint(nsIPresContext& aPresContext,
     nsCSSRendering::PaintBackground(aPresContext, aRenderingContext, this,
                                     aDirtyRect, rect, *myColor, 0, 0);
     
-    //XXX: this could be calculated once and remembered
-    // get border padding values
-    //XXX: also check style for rule on rendering empty cells
-    /*
-
-    */
     // empty cells do not render their border
     PRBool renderBorder = PR_TRUE;
     if (PR_TRUE==GetContentEmpty())
@@ -729,45 +723,6 @@ nscoord nsTableCellFrame::GetBorderWidth(nsIFrame* aFrame, PRUint8 aEdge) const
 }
 
 
-/**
-  * Given a style context and an edge, find the padding
-  *
-  **/
-nscoord nsTableCellFrame::GetPadding(nsIFrame* aFrame, PRUint8 aEdge) const
-{
-  nscoord result = 0;
-
-  if (aFrame)
-  {
-    const nsStyleSpacing* spacing;
-    aFrame->GetStyleData(eStyleStruct_Spacing, (const nsStyleStruct*&)spacing);
-    nsMargin  padding;
-    spacing->CalcPaddingFor(aFrame, padding);
-    switch (aEdge)
-    {
-      case NS_SIDE_TOP:
-        result = padding.top;
-      break;
-
-      case NS_SIDE_RIGHT:
-        result = padding.right;
-      break;
-
-      case NS_SIDE_BOTTOM:
-        result = padding.bottom;
-      break;
-
-      case NS_SIDE_LEFT:
-        result = padding.left;
-      break;
-
-    }
-  }
-  return result;
-}
-
-
-
 /**
   * Given an Edge, find the opposing edge (top<-->bottom, left<-->right)
   *
@@ -876,6 +831,7 @@ void nsTableCellFrame::RecalcLayoutData(nsTableFrame* aTableFrame,
   mCalculated = NS_OK;
 }
 
+
 /* ----- debugging methods ----- */
 NS_METHOD nsTableCellFrame::List(FILE* out, PRInt32 aIndent, nsIListFilter *aFilter) const
 {
diff --git a/mozilla/layout/tables/nsTableCellFrame.h b/mozilla/layout/tables/nsTableCellFrame.h
index 6bd3e74f288..dce0738f811 100644
--- a/mozilla/layout/tables/nsTableCellFrame.h
+++ b/mozilla/layout/tables/nsTableCellFrame.h
@@ -137,8 +137,6 @@ private:
 
   nscoord GetBorderWidth(nsIFrame* aFrame, PRUint8 aEdge) const;
 
-  nscoord GetPadding(nsIFrame* aFrame, PRUint8 aEdge) const;
-
   PRUint8 GetOpposingEdge(PRUint8 aEdge);
 
   void CalculateBorders(nsTableFrame* aTableFrame,
diff --git a/mozilla/layout/tables/nsTableFrame.cpp b/mozilla/layout/tables/nsTableFrame.cpp
index fbc069f03d4..51338353afd 100644
--- a/mozilla/layout/tables/nsTableFrame.cpp
+++ b/mozilla/layout/tables/nsTableFrame.cpp
@@ -1178,7 +1178,9 @@ void nsTableFrame::AppendLayoutData(nsVoidArray* aList, nsTableCellFrame* aTable
   }
 }
 
-void nsTableFrame::RecalcLayoutData()
+/* compute all the collapsed borders between aStartRowIndex and aEndRowIndex, inclusive */
+void nsTableFrame::ComputeCollapsingBorders(PRInt32 aStartRowIndex,
+                                            PRInt32 aEndRowIndex)
 {
   nsCellMap *cellMap = GetCellMap();
   if (nsnull==cellMap)
@@ -1186,6 +1188,77 @@ void nsTableFrame::RecalcLayoutData()
 
   PRInt32 colCount = cellMap->GetColCount();
   PRInt32 rowCount = cellMap->GetRowCount();
+  if (aStartRowIndex>=rowCount)
+  {
+    NS_ASSERTION(PR_FALSE, "aStartRowIndex>=rowCount in ComputeCollapsingBorders");
+    return; // we don't have the requested row yet
+  }
+
+  // For every row between aStartRowIndex and aEndRowIndex (or the end of the table),
+  // walk across every edge and compute the border at that edge.
+  // Distribute half the computed border to the appropriate adjacent objects
+  // (always a cell frame or the table frame.)  In the case of odd width, 
+  // the object on the right/bottom gets the extra portion
+  PRInt32 rowIndex = aStartRowIndex;
+  for ( ; rowIndex<rowCount && rowIndex <=aEndRowIndex; rowIndex++)
+  {
+    PRInt32 colIndex=0;
+    for ( ; colIndex<colCount; colIndex++)
+    {
+      /*
+      
+      // compute vertical edges
+      if (0==colIndex)
+      { // table is left neighbor
+        ComputeLeftBorderForEdgeAt(rowIndex, colIndex);
+      }
+      ComputeRightBorderForEdgeAt(rowIndex, colIndex);
+
+      // compute horizontal edges
+      if (0==rowIndex)
+      {
+        ComputeTopBorderForEdgeAt(rowIndex, colIndex);
+      }
+      ComputeBottomBorderForEdgeAt(rowIndex, colIndex);
+
+
+      if ((colCount-1)==colIndex)
+      { // table is right neighbor
+      }
+      else
+      { // interior cell
+      }
+
+      if ((rowCount-1)==rowIndex)
+      {
+      }
+      else
+      {
+      }
+
+      */
+
+    }
+  }
+}
+
+void nsTableFrame::RecalcLayoutData()
+{
+  nsCellMap *cellMap = GetCellMap();
+  if (nsnull==cellMap)
+    return; // no info yet, so nothing useful to do
+  PRInt32 colCount = cellMap->GetColCount();
+  PRInt32 rowCount = cellMap->GetRowCount();
+  
+  // compute all the collapsing border values for the entire table
+  // XXX: it would be nice to make this incremental!
+  const nsStyleTable *tableStyle=nsnull;
+  GetStyleData(eStyleStruct_Table, (const nsStyleStruct *&)tableStyle);
+  if (NS_STYLE_BORDER_COLLAPSE==tableStyle->mBorderCollapse)
+    ComputeCollapsingBorders(0, rowCount-1);
+
+  //XXX need to determine how much of what follows is really necessary
+  //    it does collapsing margins between table elements
   PRInt32 row = 0;
   PRInt32 col = 0;
 
@@ -3591,17 +3664,6 @@ void nsTableFrame::MapBorderMarginPadding(nsIPresContext& aPresContext)
 }
 
 
-
-
-// Subclass hook for style post processing
-NS_METHOD nsTableFrame::DidSetStyleContext(nsIPresContext& aPresContext)
-{
-#ifdef NOISY_STYLE
-  printf("nsTableFrame::DidSetStyleContext \n");
-#endif
-  return NS_OK;
-}
-
 NS_METHOD nsTableFrame::GetCellMarginData(nsTableCellFrame* aKidFrame, nsMargin& aMargin)
 {
   nsresult result = NS_ERROR_NOT_INITIALIZED;
diff --git a/mozilla/layout/tables/nsTableFrame.h b/mozilla/layout/tables/nsTableFrame.h
index 9c6b10ef4ef..32fbc182b63 100644
--- a/mozilla/layout/tables/nsTableFrame.h
+++ b/mozilla/layout/tables/nsTableFrame.h
@@ -207,6 +207,10 @@ public:
           
   /** Calculate Layout Information */
   void    AppendLayoutData(nsVoidArray* aList, nsTableCellFrame* aTableCell);
+
+  /* compute all the collapsed borders between aStartRowIndex and aEndRowIndex, inclusive */
+  void    ComputeCollapsingBorders(PRInt32 aStartRowIndex, PRInt32 aEndRowIndex);
+
   void    RecalcLayoutData();
 
   // Get cell margin information
@@ -473,8 +477,6 @@ public:
   virtual void InvalidateColumnWidths();
 
 protected:
-  /** do post processing to setting up style information for the frame */
-  NS_IMETHOD DidSetStyleContext(nsIPresContext& aPresContext);
 
   /** Support methods for DidSetStyleContext */
   void      MapBorderMarginPadding(nsIPresContext& aPresContext);